Reichelt, winner of the 2008 super-G title, emerged triumphant on the Birds of Prey course in Eagle County, Colorado with a time of one minute, 12.78secs, denying Kjetil Jansrud a fourth consecutive World Cup race win.
Jansrud had triumphed in the downhill on Friday following a double at Lake Louise in Canada the previous weekend, but on this occasion his mark of one minute, 13.30secs was not enough to secure top spot on the podium.
Frenchman Alexis Pinturault (1:13.40secs) – third in the overall World Cup standings last season – rounded off the top three ahead of the Italian duo of Peter Fill and Dominik Paris.
But the day belonged to Reichelt, whose performance in the eighth World Cup victory of his career was in marked contrast to that of fellow Austrian Hirscher.
The defending overall champion headed into the season looking to become the first man to win four straight overall World Cup titles, but displayed none of his considerable pedigree as he was forced to abandon his run after missing a gate.
The result sees the in-form Jansrud increase his lead at the top of the overall standings to 191 points over Paris, who is four ahead of third-placed Reichelt.
Hirscher's non-finish leaves him 216 points adrift in fourth, a gap that he will attempt to try and close with a win in Sunday's giant slalom race.